A rocket was fired into Israel from Gaza Strip, a territory controlled by the Islamic militant group Hamas, on Monday. It destroyed a home and reportedly injured seven people.
Israel responded by mobilizing troops at the border with Gaza Strip. It also called up reserves.
Israel also moved up tanks to the border.
And public bomb shelters have been opened up for Israeli citizens.
Prime Minister Benjamin Netanyahu cut a trip to the US short due to the violence.
Netanyahu was at the White House to watch President Trump formally recognize the Golan Heights, one of the world's most disputed territories, as part of Israel.
Addressing the rocket launched into Israel from Gaza while standing beside Trump, the Israeli leader said, "Israel will not tolerate this. I will not tolerate this...Israel is responding forcefully to this wanton aggression."
As Netanyahu smiled for photos with Trump, Israel’s military on Monday struck Hamas targets in Gaza Strip, and at least seven Palestinians were injured.
The targets Israel struck reportedly included Hamas military intelligence headquarters and the office of Hamas leader Ismail Haniyeh.
Despite reports of a ceasefire, cross-border strikes continued into Tuesday.
The Palestinian ambassador to the UN on Tuesday said the recent violence is "part of the long-running campaign of violence and terror being waged against our people by Israel."
The fighting between Israel and Gaza this week comes a little less than two weeks after rockets were fired from Gaza toward Tel Aviv. Israel retaliated amid reports the Hamas rocket was launched by mistake.
This also comes after two Palestinians were reportedly killed by Israeli forces during protests at the border last Friday.
The last major Israel-Hamas conflict took place in 2014 and lasted 50 days. By the end, over 2,000 Palestinian — many of them civilians — had been killed. 73 Israelis were also killed in the fighting.
The recent fighting comes roughly two weeks before Israel's national elections. Netanyahu is running for reelection and has faced criticism from some right-wing figures in Israel who feel he's not been aggressive enough with Hamas.
As Netanyahu deals with this situation amid an uncertain political future, Hamas in recent days has been clamping down on protests in Gaza against living conditions there. Hamas has responded violently to the dissent, beating and arresting demonstrators.
Meanwhile, amid the violence in Gaza, the American Israel Public Affairs Committee (AIPAC) was holding its annual policy conference from Sunday to Tuesday. Netanyahu delivered remarks via satellite, touting the historic partnership between the US and Israel.